Method and apparatus for accurate die-cutting

ABSTRACT

Inaccurate cuts often occur in paperboard blanks passing between a pair of cooperating die and anvil cylinders because of anvil cylinder wear, irregular blank velocity, and other factors. Such inaccuracies are reduced by the method of driving the die cylinder at a preselected angular velocity and driving the anvil cylinder at an angular velocity proportional to the angular velocity of the die cylinder with the preselected proportion being maintained during changes in angular velocity of the die cylinder. The apparatus generally preferred for performing the method includes a mechanical variable speed transmission having an input driven by the die cylinder and an output for driving the anvil cylinder at an angular velocity corresponding to the angular velocity of the input and with the output velocity being selectively variable with respect to the input to provide an output velocity selectively proportional to the input velocity. However, the apparatus primarily preferred for performing the method includes a sensor means for sensing the velocity of the die cylinder, a variable speed motor means for driving the anvil cylinder, and a motor controller means responsive to the sensor means for controlling the output speed of the motor means to proportionally correspond to the velocity of the die cylinder, the controller means also including variable speed control means for changing the proportion of the anvil cylinder velocity to the die cylinder velocity by changing the output speed of the motor means. Another embodiment utilizes a mechanical variable speed transmission means in lieu of the motor means and a ratio control motor means responsive to the sensor through a similar motor controller means for varying the output of the transmission means to achieve a preselected proportion which is maintained during changes in velocity of the die cylinder.



1. Apparatus for controlling the accuracy of cuts made in a paperboard blank passing between a pair of cooperating die and anvil cylinders comprising: first drive means for rotating said die cylinder at a first angular velocity; second drive means for rotating said anvil cylinder at a second angular velocity; and selection means for controlling second second drive means to selectively change and maintain the second velocity equal to, faster, or slower than said first angular velocity; for controlling the velocity of said blank.
 2. The apparatus of claim 1 and: control means for selectively changing said first angular velocity, said second drive means being directly responsive to changes in said first angular velocity for maintaining said second angular velocity selectively proportional to said first angular velocity.
 3. The apparatus of claim 1 and: sensing means for sensing said first angular velocity, said second drive means being responsive to said sensing means for rotating said anvil cylinder at said second angular velocity selectively proportional to said first velocity.
 4. The apparatus of claim 3 and: control means for selectiveley changing said first angular velocity, said sensing means producing a signal corresponding to changes in said first angular velocity, said second drive means being responsive to said signal for maintaining said second angular velocity selectively proportional to said first angular velocity.
 5. Apparatus for controlling the accuracy of cuts made in a paperboard blank passing between a pair of Cooperating die and anvil cylinders comprising: first drive means for rotating said die cylinder at a first angular velocity; sensing means for sensing said first angular velocity; and a variable-ratio electric motor means for rotating said anvil cylinder at a second angular velocity selectively proportional to said first angular velocity in response to said sensing, for controlling the velocity of said blank.
 6. The apparatus of claim 5 and: control means for selectively changing said first angular velocity, said sensing means producing a signal corresponding to changes in said first angular velocity, said motor means being responsive to said signal for maintaining said second angular velocity selectively proportional to said first angular velocity.
 7. The apparatus of claim 5 and: selection means for changing an angular output velocity of said motor means thereby changing the proportion of said second angular velocity with respect to said first angular velocity.
 8. The apparatus sof claim 5 and: a speed selector means responsive to said sensing means; and a motor controller means responsive to a signal from said speed selector means for controlling an angular output velocity of said motor means.
 9. Apparatus for controlling the accuracy of cuts made in a paperboard blank passing between a pair of cooperating die and anvil cylinders comprising: first drive means for rotating said die cylinder at a selected angular velocity; second drive means for rotating said anvil cylinder at a second angular velocity; advancing means for passing said blank between said cylinders for making cuts therein; measuring means for measuring the accuracy of cuts made in said blank; and selection means for controlling said second drive means to selectively change and maintain said second velocity equal to, faster, or slower than said first angular velocity following the measuring of inaccurate cuts in said blank to control the accuracy of cuts made in succeeding blanks passing between said cylinders.
 10. Apparatus for controlling the accuracy of cuts made in a paperboard blank passing a pair of cooperating die and anvil cylinders comprising: first drive means for rotating said anvil cylinder at a first angular velocity; second drive means for rotating said die cylinder at a second angular velocity; and selection means for controlling said second drive means to selectively change and maintain said second velocity equal to, faster, or slower than said first angular velocity. for controlling the velocity of said blank. 